Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers
DESCRIPTION
The MAX485 is a half-duplex transceiver that meets the
specifications of RS-485 and RS-422. Its BiCMOS
design allows low power operation without sacrificing
performance. The MAX485 meets the requirements of
the RS-485 and RS-422 protocols up to 5Mbps
underload. The ESD tolerance is more than
±8kV
for
both Human Body Model and
±15kV
for IEC61000-4-2
Air Discharge Method on this device.
DIP-8
SOP-8
MAX485
FEATURES
• Single +5V Supply
• Low Power BiCMOS
• Driver/Receiver Enable for Multi-Drop Configurations
• Half-Duplex Versions Available
• Data rate: 5 Mbps
• ESD Specifications
-
±15kV
IEC61000-4-2 Air Discharge
-
±8kV
Human Body Model
Inputs
RE
X
X
0
1
DE
1
1
0
0
Inputs
RE
0
0
DE
0
0
0
0
A-B
≥
+0.2V
≤
-0.2V
Open
X
TRUTH TABLE
Transmission
Outputs
DI
1
0
X
X
Receiver
Outputs
RO
1
0
1
Z
A
1
0
Z
Z
B
0
1
Z
Z
APPLICATIONS
• Low Power RS-485 Systems
• DTE-DCE Interface
• Packet Switching
• Local Area Networks
• Data Concentration
• Data Multiplexers
• Integrated Services Digital Network (ISDN)
PIN CONFIGRUATION AND LOGIC DIAGRAM
0
1
RO 1
RE 2
DE 3
DI
4
R
8 VCC
7
6
B
A
D
5 GND
Apr. 2019_R1.1
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HTC
Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers
ABSOLUTE MAXIMUM RATINGS
Characteristic
Supply Voltage
Control Input Voltage
Driver Input Voltage
Driver Output Voltage
Receiver Input Voltage
Receiver Output Voltage
Junction Temperature
Storage Temperature Range
MAX485
Unit
V
V
V
V
V
V
°C
°C
Symbol
V
CC
V
DE
, V
RE
V
DI
A, B
A, B
V
RO
T
J
T
STG
Min
Max
7
-0.3
-0.3
-15
-15
-0.3
-40
-65
V
CC
+ 0.5
V
CC
+ 0.5
15
15
V
CC
+ 0.5
125
150
RECOMMENDED OPERATING CONDITIONS
Characteristic
Supply Voltage
Operating Ambient Temperature Ranges
Symbol
V
CC
T
A
Min
4.75
-40
Max
5.25
85
Unit
V
°C
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HTC
Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers
PIN CONFIGURATION
MAX485
1
8
7
MAX485ED
6
5
SOP-8
1
2
MAX485EN
3
4
DIP-8
8
7
2
3
4
6
5
PIN DESCRIPTION
SOP-8 / DIP-8 PKG
Pin No.
Name
1
2
3
4
5
6
7
8
RO
RE*
DE
DI
GND
A
B
V
CC
Receiver Output
Receiver Output Enable Active Low
Driver Output Enable Active High
Driver Input
Ground
Non-inverting Driver Output and Receiver Input
Inverting Driver Output and Receiver Input
Power Supply: 4.75V to 5.25V
Function
Apr. 2019_R1.1
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HTC
Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers
ELECTRICAL CHARACTERISTICS
Unless otherwise specified: V
CC
= 5V ± 5%, T
A
= T
MIN
to T
MAX
PARAMETER
DRIVER DC Characteristics
Differential Driver Output
(no load)
Differential Driver Output
(with load)
Change in Magnitude of Driver
Differential Output Voltage for
Complementary Output States
Driver Common-Mode Output Voltage
Change in Magnitude of Driver
Common-Mode Output Voltage for
Complementary Output States
Input High Voltage
Input Low Voltage
Input Current
Driver Short Circuit Current
Driver Short-Circuit Current,
V
O
= High
Driver Short-Circuit Current,
V
O
= Low
DRIVER AC Characteristics
Max. Transmission Rate
Driver Input to Output
Driver Output Skew to Output
Driver Rise or Fall Time
Driver Enable to Output High
Driver Enable to Output Low
Driver Disable Time from Low
Driver Disable Time from High
RECEIVER DC Characteristics
Receiver Differential Threshold
Voltage
Receiver Input Hysteresis
Receiver Output High Voltage
Receiver Output Low Voltage
Three-State (High Impedance) Output
Current at Receiver
Receiver Input Resistance
Input Current (A, B)
Receiver Short-Circuit Current
Symbol
CONDITIONS
MIN
TYP
MAX485
MAX
UNITS
V
OD1
V
OD2
ΔV
OD
V
OC
ΔV
OC
V
IH
V
IL
I
IN1
R
L
= ∞, Figure 1
R
L
= 50Ω (RS-422), Figure 1
R
L
= 27Ω (RS-485), Figure 1
R
L
= 27Ω or 50Ω, Figure 1
R
L
= 27Ω or 50Ω, Figure 1
R = 27Ω or 50Ω, Figure 1
DE, DI, RE*
DE, DI, RE*
DE, DI, RE*
-7V ≤ V
O
≤ 12V
-7V ≤ V
O
≤ 12V
GND
2
1.5
V
CC
V
CC
V
CC
0.2
3
0.2
V
V
V
V
V
V
V
uA
2.0
0.8
±10
I
OSD1
I
OSD2
±250
±250
mA
mA
f
MAX
t
DPLH
t
DPHL
t
SKEW
t
r
, t
f
t
ZH
t
ZL
t
HZ
t
LZ
5
Figure 3 & 5
R
L
= 54Ω, C
L1
= C
L2
= 100pF
S
2
closed
S
1
closed
S
2
closed
S
1
closed
30
30
5
15
40
40
40
40
60
60
10
40
70
70
70
70
Figure 4 & 6
C
L
=100pF
Mbps
ns
ns
ns
ns
ns
ns
ns
ns
V
TH
ΔV
TH
V
OH
V
OL
I
OZR
R
IN
I
IN2
I
OSR
-7V ≤ V
CM
≤ 12V
V
CM
= 0V
I
O
= -4mA, V
ID
= +200mV
I
O
= +4mA, V
ID
= -200mV
0.4V ≤ V
O
≤ 2.4V, RE* = 5V
-7V ≤ V
CM
≤ 12V
DE = 0V
V
CC
= 0V or 5.25V
0V ≤ V
O
≤ V
CC
V
IN
= 12V
V
IN
= -7V
-0.2
20
3.5
0.2
V
mV
V
V
uA
kΩ
0.4
±1
12
15
1.0
-0.8
95
mA
mA
7
Apr. 2019_R1.1
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HTC
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